(Prior Art)
Some of lying furniture such as beds and stretchers are respectively provided with a back bottom section for lifting the back portion of a lying person and a knee bottom section for lifting his/her knee portion, which can be respectively lifted by lifting mechanisms respectively provided for them.
Many examples of such lying furniture can be seen in U.S. Pat. Nos. 5,469,591, 5,448,789, 5,388,290, etc.
For example, the bed described in U.S. Pat. No. 5,469,591 has a back bottom section for lifting the back portion of a lying person, a knee bottom section for lifting his/her knee portion, and other bottom sections. On the undersides of the back bottom section and the knee bottom section, lifting arms each having a roller at the tip are installed pivotally rotatably, and the lifting arms can be driven and rotated by electric drive mechanisms such as motors.
In this constitution, the lifting arm of the back bottom section is pivotally rotated to let its roller lift the back bottom section in a pivotally rotating motion, for making it inclined, thereby lifting the back of the lying person, so that he/she can get up on the bed.
When the back bottom section is lifted and inclined like this, the lifting arm of the knee bottom section is pivotally rotated to let its roller lift the knee bottom section in a pivotally rotating motion, for making it inclined, thereby effectively preventing that the lying person slides forward if the back bottom section only is lifted.
That is, in the case where the person lying on the bed is lifted at his/her back, to get up, if the back bottom section is lifted, his/her body gradually slides forward since he/she is pressed forward at his/her back by the back bottom section. As a result, the point at which his/her body can be easily bent shifts from the pivot of the back bottom section. So, a force for bending the lumbar vertebra portion unlikely to be bent is applied from the back bottom section, to press the lumber vertebra portion and the abdominal portion of the lying person, making him/her feel displeasure.
Therefore, if the knee bottom section is lifted when the back bottom section is lifted, the body portion located above the inclined knee bottom section, i.e., femoral regions can receive the force applied from the back bottom section to press the lying person forward. As a result, the downward body sliding and displeasure feeling caused when his/her back only is lifted by means of the back bottom section can be prevented.
The conventional methods for also lifting the knee bottom section when lifting the back bottom section include, for example, the following.
a. As a first example, the drive mechanisms for lifting the back bottom section and the knee bottom section are operated respectively independently, and the lying person per se or a nurse simultaneously or alternately turns on and off the respective drive mechanisms, using, for example, remote control switches, to lift the back bottom section and the knee bottom section respectively to desired positions.
b. As a second example, a common motor or the like is used to drive the drive mechanisms of the back bottom section and the knee bottom section using an interlocking mechanism such as a link mechanism, so that the drive mechanisms of the back bottom section and the knee bottom section can be actuated in a mechanically interlocked manner, to lift the back bottom section and the knee bottom section to predetermined positions.
(Problems of the Prior Art)
However, these conventional methods have the following problems.
A. In the method a, the lying person or a nurse must simultaneously or alternately operate the respective drive mechanisms of the back bottom section and the knee bottom section. This operation is very complicated and troublesome, and the operator must be accustomed to it. Furthermore, it is difficult to always reproduce the optimum lifting states respectively for the back bottom section and the knee bottom section.
B. In the method b, since an interlocking mechanism is used, the lifting states of the back bottom section and the knee bottom section achieved in an interlocked manner are inevitably simple and cannot be adjusted or changed, and it is difficult to efficiently prevent both the downward body sliding and the displeasure feeling such as pressure feeling. Furthermore, the back bottom section and the knee bottom section cannot be operated respectively independently.
C. In both the methods a and b, if the knee bottom section is lifted when the back bottom section is lifted, the back bottom section lifts the back of the lying person with his/her waist portion supported by the lifted knee bottom section, it arises that the back of the lying person tends to slide upwardly against the frictional resistance. So, the external force in the sliding direction caused by the frictional acting between his/her back and the back bottom section, hence a mattress, acts on his/her back, and if the lifting of the back bottom section and the lifting of the knee bottom section continue without any control, the angle formed between the back bottom section and the knee bottom section becomes gradually small to gradually bend his/her abdominal region, finally letting him/her feel a pressure.